1) Field of the Invention
This invention relates to a polypeptide having anticoagulant activities like a placental coagulation inhibitor (hereinafter called "PCI") available from human tissues led by the human placenta, a novel DNA coding the polypeptide, a recombinant plasmid containing the DNA, a transformant containing the recombinant plasmid, an anticoagulant containing the polypeptide as an effective ingredient and a process for the production of the polypeptide.
2) Description of the Prior Art
Heparin, heparin cofactor-II, antithrombin-III, .alpha..sub.2 -macroglobulin, .alpha..sub.1 -trypsin inhibitor, C.sub.1 -esterase inhibitor, protein C and the like have conventionally been known as anticoagulants. It is however only heparin that has found practical utility. Heparin however has a side effect of inducing bleeding tendency. Extremely stringent limitations are therefore imposed on its manner of administration and its dosage. Heparin has hence been not satisfactory as an anticoagulant from the standpoint of safety.
Under the aforementioned circumstances, the present applicant has already succeeded in separating and purifying PCI from the human placenta, on which an application has been filed (Japanese Patent Application No. 217512/1985).
PCI is a substance which has the following properties and is useful as a medicine.
(1) Molecular weight (SDS-polyacrylamide gel electrophoresis, reduced state): 34,000.+-.2,000. PA1 (2) Isoelectric point (isoelectric column electrophoresis using an ampholyte): 4.7.+-.0.1. PA1 (3) Stability: PA1 (4) Effects: PA1 (5) Analysis of amino acids:
(a) Inactivated by a heat treatment at 50.degree. C. for 30 minutes. PA2 (b) Stable in a pH range of 4-10. PA2 (c) Stable in plasma at 37.degree. C. for 30 minutes. PA2 (a) Capable of prolonging the recalcification time. PA2 (b) Capable of prolonging the prothrombin time. PA2 (c) Capable of prolonging the activated partial thromboplastin time. PA2 The existence of aspartic acid, threonine, serine, glutamic acid, proline, glycine, alanine, 1/2 cystine, valine, methionine, isoleucine, leucine, tyrosine, phenylalanine, histidine, lysine and arginine is recognized by the analysis of amino acids.
The present applicant has also prepared a monoclonal antibody specific to PCI and already filed an application for patent thereon (Japanese Patent Application No. 269588/1986). It is feasible to perform high-sensitivity assay, purification, etc. of the PCI by using this monoclonal antibody.
Several problems have however arisen because human tissues typified by human placentae are presently indispensable as a raw material for obtaining PCI. For example, there is a limitation imposed on the quantity of PCI available from a human tissue. Difficulties are always accompanied upon collection of human tissues as a raw material, whereby stable supply of the raw material is difficult. In addition, the potential danger of pathogenic viruses which may be contained in human tissues is not ignorable.
It has hence been desired to develop a method for supplying PCI at a lower price, in a larger volume, more stably and more safely or to develop a substance having effects similar to PCI.